January 11 – LaGrange College (now the University of North Alabama) began operation, becoming the first publicly chartered college in Alabama.
January 12–January 27 – Webster–Hayne debate: Robert Y. Hayne of South Carolina debates the question of states' rights vs. federal authority with Daniel Webster of Massachusetts in the United States Congress.
February 3 – The London Protocol establishes the full independence and sovereignty of Greece from the Ottoman Empire as the final result of the Greek War of Independence.
March 12 – Craig vs. Missouri: The United States Supreme Court rules that state loan certificates are unconstitutional because they were bills of credit emitted by a state in violation of Article I, Section 10 of the Constitution.
March 26 – The Book of Mormon is published in Palmyra, New York.
April 6 – Joseph Smith and five others organize the Church of Christ (later renamed the Church of Jesus Christ of Latter Day Saints), the first formally organized church of the Latter Day Saint movement, in northwestern New York.
May 13 – Ecuador separates from Gran Colombia.
May 28 – The United States Congress passes the Indian Removal Act, authorizing the President to negotiate with Native Americans in the United States for their removal from their ancestral homelands.
June 26 – William IV succeeds his brother George IV as King of the United Kingdom.
July 5 – France invades Algeria (see French Algeria).
July 13 – The General Assembly's Institution, now the Scottish Church College, one of the pioneering institutions that ushered the Bengali renaissance, is founded by Alexander Duff and Raja Ram Mohan Roy, in Calcutta, India.
July 17 – Barthélemy Thimonnier is granted a patent (#7454) for a sewing machine in France; it chains stitches at 200/minute.
July 18 – Uruguay adopts its first constitution.
July 20 – Greece grants citizenship to Jews.
July 27 – France: The July Revolution begins (see also 1830 in France).
August 9 – France: Louis Philippe becomes King of the French.
August 13 – France: Duc de Broglie becomes Prime Minister.
August 25 – The Belgian Revolution begins.
August 31 – Edwin Beard Budding is granted a patent for the invention of the lawn mower.
September 15 – The Liverpool and Manchester Railway opens, the world's first intercity passenger railway operated solely by steam locomotives.
September 27 – The Belgian Revolution ends by liberating Brussels from the United Kingdom of the Netherlands.
October 4 – The Provisional Government in Brussels declares the creation of the independent state of Belgium, in revolt against the United Kingdom of the Netherlands.
October – Start of the Regeneration in Switzerland: more liberal constitutions adopted in most cantons.
November 2 – France: Jacques Laffitte succeeds the Duc de Broglie as Prime Minister.
November 8 – Ferdinand II becomes King of the Two Sicilies.
November 22 – The Whig Charles Grey, 2nd Earl Grey succeeds Arthur Wellesley, 1st Duke of Wellington as Prime Minister of the United Kingdom.
November 29 – The Polish insurrection begins in Warsaw against Russian rule.
December 5 – Hector Berlioz's most famous work, Symphonie fantastique, has its world premiere in Paris.
December 20 – The independence of Belgium is recognized by the Great Powers.
The Java War ends.
10,000 chests of opium are sold in China.
Austins of Derry established in Northern Ireland. Until closure in 2016, it was the world's oldest independent department store.
January 21 – Liu Kunyi, Chinese general (d. 1902)
January 23 – Gaston Alexandre Auguste, Marquis de Galliffet, French general (d. 1909)
January 31 – James G. Blaine, 28th and 31st United States Secretary of State (d. 1893)
February 3 – Robert Gascoyne-Cecil, 3rd Marquess of Salisbury, Prime Minister of the United Kingdom (d. 1903)
February 9 – Abdülaziz, Ottoman Sultan (d. 1876)
March 15 – Paul Heyse, German writer, Nobel Prize laureate (d. 1914)
March 30 – Mihály Zsupánek Slovene writer, poet and soldier in Hungary (d. 1898? 1905)
May 5 – John Batterson Stetson, American hat maker (d. 1906)
May 9 – Harriet Lane, Acting First Lady of the United States (d. 1903)
May 10 – François-Marie Raoult, French chemist (d. 1901)
May 14 – Antonio Annetto Caruana, Maltese archaeologist and author (d. 1905)
May 29 – Louise Michel, French anarchist (d. 1905)
April 9 – Eadweard Muybridge, English photographer, pioneer of photographic studies of motion (d. 1904)
April 19 – Pierre Paul Dehérain, French chemist and botanist (d. 1902)
April 21 – Clémence Royer, French anthropologist (d. 1902)
June 5 – Carmine Crocco, Italian brigand (d. 1905)
July 10 – Camille Pissarro, French painter (d. 1903)
July 20 – Fanny Janauschek, Czech-born actress (d. 1904)
July 25 – John Jacob Bausch, German-American optician who co-founded Bausch & Lomb (d. 1926)
August 18 – Emperor Franz Joseph I of Austria (d. 1916)
September 2 – William P. Frye, American politician (d. 1911)
September 8 – Frédéric Mistral, French writer, Nobel Prize laureate (d. 1914)
September 12 – William Sprague IV, American politician from Rhode Island (d. 1915)
September 15 – Porfirio Díaz, President of Mexico (d. 1915)
September 20 – Edward James Reed, British naval architect, author, politician, and railroad magnate (d. 1906)
September 22 – Caroline Webster Schermerhorn Astor, prominent American socialite (d. 1908)
November 7 – Emanuele Luigi Galizia, Maltese architect and civil engineer (d. 1907)
December 10 – Emily Dickinson, American poet (d. 1886)
December 17 – Jules de Goncourt, French writer (d. 1870)
December 21 – Bartolomé Masó, Cuban patriot (d. 1907)
Mary Hunt, American activist (d. 1906)
Su Sanniang, Chinese rebel (d. 1854)
January 7 – Thomas Lawrence, English painter (b. 1769)
January 7 – John Campbell, Australian public servant and politician (b. 1770)
January 25 – Benito de Soto, Galician pirate (b. 1805)
February 2 – Manoel da Costa Ataíde, Brazilian artist (b. date unknown)
February 23 – Jean-Pierre Norblin de La Gourdaine (Jan Piotr Norblin), French-born Polish artist (b. 1740)
March 7 – Jacques Villeré, first Creole governor of Louisiana (b. 1761)
March 17 – Laurent de Gouvion Saint-Cyr, French marshal (b. 1764)
June 1 – Sahajanand Swami (Swaminarayan), believed to be an incarnation of god by his followers, leaves his mortal body (b. 1781).
June 4 – Antonio José de Sucre, Venezuelan revolutionary leader and statesman (b. 1795)
June 26 – King George IV of the United Kingdom (b. 1762)
June 28 – David Walker, Abolitionist (b. 1796)
September 18 – William Hazlitt, British essayist (b. 1778)
September 23 – Elizabeth Monroe, wife of James Monroe, First Lady of the United States (b. 1768)
October 4 – Ludwig Yorck von Wartenburg, Prussian military leader (b. 1759)
October 5 – Dinicu Golescu, Romanian writer (b. 1777)
November 8 – Francis I of the Two Sicilies (b. 1777)
November 18 – Adam Weishaupt, German philosopher (b. 1748)
November 30 – Pope Pius VIII (b. 1761)
December 8 – Benjamin Constant, Swiss writer (b. 1767)
December 17 – Simón Bolívar, Venezuelan revolutionary leader and statesman (b. 1783)
Aleamotuʻa, King of Tonga (b. 1738)
Petar I Petrović Njegoš, ruler of Montenegro (b. 1747)
Temerl Bergson, Polish Jewish businesswoman and philanthropist
Clelia Durazzo Grimaldi, Italian botanist (b. 1760)
1830 (MDCCCXXX) was a common year starting on Friday (dominical letter C) of the Gregorian calendar and a common year starting on Wednesday (dominical letter E) of the Julian calendar, the 1830th year of the Common Era (CE) and Anno Domini (AD) designations, the 830th year of the 2nd millennium, the 30th year of the 19th century, and the 1st year of the 1830s decade. As of the start of 1830, the Gregorian calendar was 12 days ahead of the Julian calendar, which remained in localized use until 1923. It is known in European history as a rather tumultuous year with the Revolutions of 1830 in France, Belgium, Poland, Switzerland and Italy.